Grinding mill



GRINDING MILL Aug. v16, 1932. H. HARDINGE GRINDING MILL Filed July 22. 1929 2 sheets-Sheet 2 3 36' 34 lfwwf Mika/N@ Patented Aug. 16, 1932 UNITED STATES PATENT OFFICE HARLOWE HARDINGE, F YORK, PENNSYLVANIA, ASSIGNOR T0 HARDINGE COMPANY, INCORPORATED, 0F YORK, PENNSYLVANIA, A CORPORATION OF NEW YORK GRINDING MILL Application led July 22,

This invention relates to grinding mills, and particularly to linings and features appurtenant to their use in conical mills.

Among the objects of this invention is to improve the operating characteristics of a rotary grinding mill and particularly of a mill of such type as has a conical wall enclosing a portion of its grinding volume. Improved operating characteristics are attained by the use of a novel principle in the arrangement of the linings of a mill whereby, instead of resorting to lifter bars for preventing material and balls from sliding as a mill rotates, I provide a lining having longitudinal de-pressionsor grooves with sloping sides which, as to the balls and coarse material in the conical'portion at the discharge end of a conical mill, cause rapid movement thereof toward the outward or discharge end of the mill on the rising side of the mass and a deiiection of the balls downward and inward toward the cylindrical portion of the mill on the falling side of the mass. A rapid circulating effect of the balls and material undergoing reduction may thereby be achieved.

Another objectof the invention is to provide a lining made up of lining members having depressions either individual to one or to a number of adjacent lining members and which have sides so sloped as to attain the object primarily stated, and yet which has utility as lining for any type of grinding mill whatsoever and in any part or parts thereof.

Another object of the invention is to provide a conical type of rotary grinding mill having a wall in its conical discharge portion limiting the grinding length'of the mill but which, in conjunction with the novel form of depression lining plates, does not produce a more limited grinding capacity than if the Wall were not used and such a type of mill were provided with lifter bars upstanding from the surface of the lining as has been the practice heretofore.

Further and otherobjects and advantages incident to and related to the foregoing objects will be pointed out hereinafter in the description which follows and in the annexed claims.

5 In the drawings, Fig. 1 -is a longitudinal 1929. semi no. 379,898.

section of a mill embodying the invention.

Figs. 2, 3, 4 and 5 are cross-sectional details of different types of lining members embodying features of the invention and illustrating how such linin"r members may be maintained in position within a mill.

Referring to Fig. 1, the invention is illustrated in conj unctionlwith a well known type of mill generally designated'as theHardinge mill or as a conical mill. The operating characteristics of this type of mill are disclosed in United States Patent No. 908,861, to which reference may bemade, since the present disclosure touches thereon only to the extent necessary for a. full understanding of the present invention.

The conical mill illustrated is supported for rotation on trunnions l0, 11, which are hollow, and through which material may pass. Material is taken into the mill at its "0 feed end by means of a scoop feeder 12, and passes out as pulverized'material (with or Without water) at the discharge end 13.l

The shell or drum 14 of the mill has three sections or portions, a cylindrical section 15, a'conical section 16 at its feed end and a conical section 17 at its discharge end. The drum is made of relatively thin material, and in order to protect it, it is customary to provide a lining of suitable thickness which is usually attachable in sections so that it, or sections thereof, may be replaced when such action becomes desirable.

It is understood that in this type of mill when a grinding operation is taking place the larger balls and pieces of material will remain within or in the vicinity of the cylindrical portion 15 and that the other balls and pieces of material will be arranged in the conical portions 16, 17, and particularly in conical portion.17, according to size, with the smaller balls and material graded toward theapices of the conical portlons.

Lifter bars extending above the surface lining have been used throughout mills to prevent slippage of material and to cause agitation, but, in view of the rinciples I have discovered, I dispenseA with suchin the lining of the conical discharge portion 17, and may do so in the Icylindrical portion 15 and in the vIl() vconical feed portion 16. However, I have illustrated in the cylindrical portion and in the conical feed portion lining members 18 and lifter bars 19 which operate in their usual Flor the lining of the conical discharge end I embody the principles of my invention which are particularly applicable in such relation though possessing advantages in connection with linings in other portions of a mill. In the discharge conical end 17 no lifter bars are provided, and my invention takes the form of depressions which prevent slippage as well as increase agitation, and otherwise improve the operating characteristics of the mill. Ihe depressions may take the form illustrated in Figs. 1 and 2 or any other form, such as, for example, one of the forms illustrated in Figs. 3, 4 and 5.

The depression is characterized by running longitudinally of a lining plate or member or of the shell or drum 14 of the mill, and has sides which sl-ope at an angle of approximately 17 to the radius of the drum with the apex of the sides of a single depression pointing away from the center of the drum. Each depression has a depth preferably exceeding one-half the thickness of a lining member.

As illustrated in Figs. 1 and 2, the longitudinal edges 2O of lining members 21 are beveled, and the edges at the widest portion of the lining members contact with similar edges of adjacent plates. Each plate is provided with two holes 22, each having two parallel sides and two tapering sides which are engaged by the head 23 of a bolt. While these bolts may take various forms, it is better that they may be tightened from the outer side of the mill.

The depressions formed in the manner illustrated in Fig. 3 necessitates the use of chan nel bars 24 with sloping flanges to engage the beveled edges 25 of lining members 26. Ordinary bolts 27 may be used in this instance.

Each of the depressions 28 illustrated in Fig. 4 is related to a single lining member 29. The depression takes the form of a longitudinal groove having sloping sides and of a depth preferably exceeding one-half of the thickness of a lining plate. Bolts 30, as in other instances, serve to hold the lining member in proper position.

Fig. 5 illustrates a manner of providing a de ression which I regard as very desirable.

.ach member comprises a plate 31 with two opposite edges 32, 33, beveled and recessed at 34, 35. When the plates 31 are mounted within a mill wear pieces 36 are positioned so as to be engaged by, and lie between, a pair of recesses 34, 35, of adjacent plates 31. The wear pieces are provided to save the drum 14 of the mill from wear and they will so perform even though the edges of the lining members 31 become worn. Taper headed bolts 37 are useful to hold the lining members 31 and wear pieces 36 in position. It is apparent that the groove 33 formed in the manner illustrated in Fig. 5, may take the form of depression 28, illustrated in Fig. 4, and otherwise conform with the spirit of the invention.

While I have found that an angle of approximately 17 o to the radius of the drum is satisfactory for a side of a depression, it will be appreciated that this angle may be varied to produce variations in result to conform with conditions desired to be met and conditions desired to have prevail within the mill.

As the mill is rotated the balls and material which have settled in the grooves is carried upwardly on the rising side of the mill to a point where cascading takes place. In the discharge conical portion material which has been carried upwardly will tumble away from the rising wall and in a direction toward ,the discharge end of the mill. The grooves embodying my invention give added impetus tothe balls and larger sizes of material as they deflect them toward the discharge end of the cone. The slope of the sides of the ygroove permit the point at which the deflection occurs to be lower than in instances where lift bars similar to lift bars 19 are used in the discharge conical portion. As the balls and material strike the receding wall of the conical discharge portion they are deflected by the sides of the receding grooves in a direction toward the cylindrical portion of the mill. The combined actions of rising and receding grooves in the conical discharge portion causes a rapid circulating effect of the balls and material undergoing reduction. The lines do not travel as fast as the balls and coarse material, nor do they strike the receding side or bottom with enough force to send them toward the cylindrical portion of the mill. As a consequence, they are propelled rapidly toward the discharge end. While the grooves or depressions in the lining of a mill may be constructed in any of several forms similar to these herein disclosed, the total area of the surface of the elevations should exceed onehalf the total area of the elevations and the area of the space across the widest portion of the depressions.

In view of the great amount of agitation which is producable by linings having grooves embodying my invention I provide, when conditions require, a wall 40 which prevents balls and coarse material from being thrown out of the discharge end of the mill. This wall has an opening 41 through which fines may pass, and it preferably is in the form of a cone reversely disposed in respect to the conical discharge portion 18. The apparent loss in volume of the grinding chamber which occurs when a reverse cone wall is used is more than ofi"- set by the gain in volume due to the use of lining members having grooves or depressions. The net result is a mill capable of carrying a large ball load and capable of producing the maximum grinding effect by violent agitation and circulation of the mass with quick discharge of the fines.

The mass of material in the mill is illustrated in a manner to approximate tumbling movements taking place when the mill is rotating in a counter-clockwise direction as viewed from the discharge end of the mill. The far wall is rising and balls a and b, upon reaching ,the highest points tol which they can be carried by a groove in the rising wall will be caused to pitch toward the discharge end of the mill, as illustrated, before dropping directly downward into contact with thereceding portion of the drum wall in the vicinity o c and d. In view of the fact that points c and d are on a receding portion of the wall of the mill, which is removed from the illustration of Fig. 1, the illustration is necessarily diagrammatic. Upon coming into contact with a groove in the receding wall of the mill the balls are deflected as from c to e and from d to f, at which positions (e, f) of their travel they become involved in the general mass of material and are carried upwardly in the general direction of the dotted lines g. 7L.

The conical wall 40 also contributes to the circulating effect desired to be had as well as operates to automatically dislod e any balls or other material which have ecome lodged in the space i. Such balls and material may be carried around with the rising wall of the drum in (the path indicated as j to a point well above the center line of the mill, from which point they will be defiected and spread by the convex surface of wall 40 along the general path l and into the grinding zone of the mill.

If, by any chance. balls pass through opening 41 and drop in the space 42 between wall 40 and the discharge end of the mill they will be returned to the grinding zone of the mill by troughs or deiectors 43. As the mill rotates any ball or oversize material which has found its way to space 42 will be picked up by a trough 43 and be caused to be guided to and through opening 41.

What I claim is:

1. In a grinding mill, the combination with a rotary drum, of a lining therefor having a plurality of longitudinally extending lining members forming alternate elevations and longitudinal depressions, each of said depressions having opposite walls sloped at an angle to the radius of the drum and converging toward a point beyond the bottom of the depression formed thereby, and means engaging the opposite sloping walls of depressions and the drumfor maintaining said lining members in place within the drum,

said means being so formed as to leavegrooves within said depressions which are adapted to receive material carried within the drum.

2. The combination set forth in claim 12 in which the means for maintaining the lining members in place include wearing pieces disposed at the bottom of said longitudinal der pressions.

3. In a grinding mill, the combination with a rotary drum, of a lining therefor having a plurality of longitudinalextending lining members, each lining member forming a part of but one elevation and two longitudinal depressions in the lining, each of said deand undercut recesses, each recess being adjacent a sloping edge at the widest side of a lining member, wearing pieces engaging within the recesses of adjacent lining members, and means maintaining the lining in place Within the drum.

5. In a grinding mill, the combination with a rotary drum having a conical wall portion with its'apex in the direction of the discharge end of the mill, of lining therefor having a plurality of lining members,'said lining members forming a plurality of alternate elevations and depressions extending longitudinally of the conical wall, each of said depressions having sides sloped toward cach other and converging on the outer side ofthe lining whereby material and rinding balls engaged by the depressions rismgfas the mill rotates are defiected toward the apexof the conical wall of the mill, and a Wall within the conical wall portion of the mill limiting the volume of the mill in which the material and grinding balls are tumbled.

6. The combination set` forth in claim 5, in which the last named wall is conical and reversely sloped in respect to the conical wall of the mill.

7. In a rinding mill, the combination with a rotary rum having a conical wall portion with its apex in the dlrection ofthe discharge end of the mill, of a separation Wall within the conical wall portion of the mill adapted to deflect grinding media away from the discharge end of the mill, said separation wall having at least one opening, and means on the discharge end side of 'said separation wall for returning grinding media or oversize material which might have passed said openmg, to the other side of said separation wall.

8. In a grinding mill, the combination with a rotary drum, of lining therefor having a plurality of lining members, said lining members forming a plurality of alternate elevations and 'depressions extending longitudinally ot the drum, each of said depressions having sdes sloped toward each other and converging on the outer side of the lining whereby material and grinding media engaged by the depressions rising as the mill rotates are deflected toward the discharge end of the mill, a separation wall within the mill adapted to deliect grinding media deflected by said depressions away from the discharge end of the mill, said separation wall having at least one opening, and means on the discharge end side of said separation wall for returning grinding media or oversize material which might have passed said opening, to the other side of said separation wall.

9. In a grinding mill, the combination ,with a rotary drum having a conical wall port-ion with its apex in the direction of the discharge end of the mill, of lining therefor having a plurality of lining members, said lining members forming a plurality of alternate elevations and depressions extending longitudinally of the conical wall, each of said depressions having sides sloped toward each other and converging on the outer side of the lining whereby material and grinding media engaged by the depressions rising as the mill rotates are deflected toward the apex of the conical wall ot the mill, a separation wall within the conical wall portion of the mill adapted to deiect grinding media deflected by said depressions away from the discharge end of the mill, said separation asV wall having at least one opening, and means on the discharge end side of said separation wall for returning grinding media or'oversize material which might have passed said opening, to the other side of said separation wall.

l0. A lining member for a grinding mill, comprising an elongated plate with beveled longitudinal edges and recesses along said edges interrupting said edges and one surface of the member, said member having holes therein for permitting engagement of said member to the mill.

11. A lining member for a grinding mill, comprising a plate with two opposite edges beveled and recessed, the bevel and recess of each edge extending from one side of the plate to the other with the bevel covering more than one-half the thickness of the plate between the two said sides.

1Q. A lining member for a grinding mill, comprising a plate having a lining surface and a convex surface opposite to said lining surface and beveled longitudinal edges intersecting said lining surface, said convex surface having recesses therein extending to an intersecting said beveled longitudinal edges.

13. In a grinding mill, the combination with a rotary drum, of an all-metallic replaceable lining therefor circumferentially disposed around the interior of the shell of the drum, the lining of said drum being shaped with alternate flats and grooves ex' tending longitudinally of the drum and of which the flats are relatively wider than the grooves, the said grooves having opposite sides separated at the bottoms of the grooves by metallic portions of said lining, said sides of said grooves diverging in such a manner that the bottoms of the grooves are narrower than the openings at their tops and the flats are narrower across their tops than the width of their bases betweenadjacent grooves.

14. In a grinding mill, the combination with a rotary drum, of an all-metallic replaceable lining therefor, the lining of said drum being shaped with alternate flats and grooves extending longitudinally of said, drum, the

bases between adjacent grooves, said lining having each flat relatively wider than the widest dimension of each groove, said lining furthermore including at least one plate for each flat and groove circumferentially disposed about the interior of the drum.

In testimony whereot` I hereto aiiix my signature.

HAR-LOWE HARDINGE. 

